<!DOCTYPE html>
<html>
    <body>
        <button id="demo">点我</button>
        <p id="demo1"></p>
        <script>
            var x = document.getElementById("demo");
            x.addEventListener("mouseover",fun1);
            x.addEventListener("click",fun2);
            x.addEventListener("mouseout",fun3);
            function fun1(){
                document.getElementById("demo1").innerHTML+="mouse over<br>";

            }
            function fun2(){
                document.getElementById("demo1").innerHTML+="Click<br>";

            }
            function fun3(){
                document.getElementById("demo1").innerHTML+="mouse out<br>";
            }
        </script>
    </body>
</html>